Various types of seat belt and airbag systems have been used to protect passengers in automobiles, aircraft, and other vehicles. In automobiles, for example, airbags typically deploy from the steering column, dashboard, side panel, and/or other fixed locations. In a typical airbag system, a sensor detects a rapid deceleration event (e.g., a collision or crash), and transmits a corresponding signal to an initiation device (e.g., a pyrotechnic device) on an airbag inflator. This causes the inflator to release compressed gas into the airbag, thereby rapidly inflating and deploying the airbag.
Although airbags that deploy from stationary locations (e.g., a steering column) may be effective in automobiles, they may not be as effective in other types of vehicles (e.g., aircraft) having other seating arrangements. As a result, airbags have been developed that deploy from seat belts to accommodate occupants in aircraft and other vehicles.
Certain types of passenger aircraft (e.g., private, commercial, or military jets), for example, can be configured with side-facing seats, divans, or rows of seating. A recent policy statement governing safety requirements for side-facing seats from the Federal Aviation Administration (FAA) includes a requirement that “[a]xial rotation of the upper-leg (femur) must be limited to 35 degrees in either direction from the nominal seated position.” See FAA policy statement PS-ANM-25-03, Technical Criteria for Approving Side-Facing Seats, dated Jun. 8, 2012. Certain manual devices requiring actuation by a seat occupant or flight attendant prior to take-off have been developed to prevent rotation of the leg (“leg flail”) in this context. However, manual devices require user actuation and may not always be activated for use, especially during situations without flight attendant oversight. Further, these devices may not be able to prevent leg flail for a full range of occupant sizes that may occupy a seat. Additionally, FAA regulations require that such devices automatically retract post-crash, requiring the retraction mechanism be resistant to crash damage. Some embodiments of airbag systems described herein can address these requirements.